Lorena Beese, Biochemistry

The broad goal of our research is to understand the biological function of macromolecules in terms of their three dimensional structure. Our strategy is to combine the techniques of macromolecular X ray crystallography with genetic and biochemical analysis to obtain high resolution three-dimensional images of the proteins and protein nucleic acid complexes central to DNA replication, repair and signal transduction. A detailed molecular picture of these proteins and substrate complexes will further our understanding of their molecular mechanisms. Ultimately such an approach should enable us to develop rational strategies for the isolation and development of new therapeutic agents for such diseases as cancer. DNA replication and repair are complex processes involving a large number of different proteins and protein nucleic acid complexes. The structures of very few of these proteins and complexes are known. We are studying the structural basis for the fidelity of DNA replication by determining the three dimensional structure of DNA polymerases with DNA substrates including mismatched nucleotides and carcinogens. Our laboratory is also carrying out structural, biochemical, and genetic studies on E. coli primase, the specialized RNA polymerase that synthesizes RNA primers essential for initiating DNA synthesis, and several proteins essential to herpes simplex virus-1 replication. In collaboration with Professor Modrich we are investigating the MutS protein which is central to methyl directed mis-match repair of DNA in E. coli. In each case, our goal is to obtain the three dimensional structures of these proteins together with appropriate DNA or RNA complexes. Such structures should also enable us to address general questions of protein-DNA recognition. A second focus of the laboratory is on structural problems in the area of signal transduction. In collaboration with Professor Casey we are determining the three dimensional crystal structure of several proteins and substrate complexes essential for signal transduction. We have recently determined the three-dimensional structure of protein farnesyltransferase (FTase), an enzyme that is considered a promising anticancer drug target by a number of pharmaceutical companies. The enzyme activates a protein known as Ras. Mutant forms of Ras are associated with up to a quarter of all cancers including 90% of all pancreatic cancers and 50% of colon cancers. Inhibition of FTase has been shown to eliminate Ras-induced tumors in mice without side effects. The crystal structure of FTase reveals details that may aid efforts to design new chemotherapy agents targeting the enzyme.